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This story is from the category Display Technology
Date posted: 03/12/2009 As technology shrinks ever smaller, interest in objects and devices on the nanoscale becomes more apparent. However, visualizing these objects in three dimensions comes with special challenges. Alexander Govyadinov, a scientist at the University of Pennsylvania, points out that imaging nano-objects in 3-D typically requires measurements of the optical phase, a task which is so difficult that it is rarely done. Govyadinov, however, believes that there is a way around this problem by using a technique that does not require phase measurements. Govyadinov and his colleagues at the University of Pennsylvania, George Panasyuk and John Schotland, have proposed a technique that could, theoretically, provide 3 D imaging of nanostructures, without the need to measure or control phases. Their work is presented in Physical Review Letters: "Phaseless Three-Dimensional Optical Nanoimaging." ?Near-field microscopy techniques have done a great deal in terms of studying very small objects,? Govyadinovsays. ?However, there are limits. One of the biggest limits is the fact that near-field techniques only allow you to see what is on the surface. You can?t go below. The object's interior, however, affects the image you obtain, such that you can get two different results when imaging the same thing using different near-field techniques.? He also points out that alternative methods for nano-imaging, such as UV and X-ray tomography, can cause damage to objects, such as occurs with degradation in nanochips, or damage to biological cells. In order to get around the aforementioned problems, Govyadinov and his peers created a new technique that involves avoiding the need for phase measurements or phase-controlled illumination altogether. ?As a proxy for the optical phase, we propose to employ the tip of a near-field microscope,? he explains. ?This tip is a small fiber, which we can use to scan all along the surface, including up and down. By shining light on both the sample and the tip and measuring how much power is scattered away, the 3-D image can be constructed.? The purpose of the near-field tip is to modify the pattern of illumination produced inside the sample, which determines the measured power. See the full Story via external site: www.physorg.com Most recent stories in this category (Display Technology): 25/05/2013: Facial Recognition Technology Proves its Mettle |
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